Bio- and chemical sensing

Sensing interfaces and biomimetic membranes

We investigate here how
the self-assembly technique can be used to design and develop novel sensing
interfaces, as well as templates for sensing interfaces. A series of differently
functionalized alkanthiolate SAMs have been prepared and tested using a surface
acoustic wave (SAW) device for the development of a gas sensor for dimethylmethylphosphonate,
a model molecule for the highly toxic sarin molecule.
We have also employed the nanoporous assemblies of thiocholesterol for the
development of electrochemical sensing surfaces for studies of fast electron
transfer kinetics and for detection of pharmaceutical compounds, like promazin.
A class of cage molecules consisting of tert-butylcalix[4]arene entities,
capable of forming inclusion complexes with small organic compounds (e.g.
toluene), has been tested and charactrerized for sensing applications together
with scientists from Eberhard-Karls Universität, Tübingen.

A considerable part of
the sensing research is devoted to the deveopment of protein rejecting and
biocompatible coatings. Sugar and polyethylene glycol-terminated SAMs are
prepared and analysed in various biofluids in an attempt to identify the critical
surface properties for obtaining layers with low non-specific binding. We
investigate, for example, layers with controlled surface energy, tail group
mobility, water binding capacity and morphology. This is a joint project with
the chemistry department, at Linköping University and the biomaterials
group at our laboratory. The group is also involved in a number of projects
aiming at the development of efficient and reliable protocols for the immobilization
of biologically complex recognition elements on 2-D and 3-D sensing interfaces.
Attachment of receptors, peptides, proteins, antibodies, oligonucleotides
and so forth are performed in collaboration with molecular biologists, farmacologists
and biomaterial scientists.

Oligo(ethylene glycol)
OEG-SAMs are also of interest for the development of a template for the attachment
of lipid bilayer structures containg functional trans-menbrane proteins onto
surfaces. The idea is to use the OEG layer as a flexible water reservoir between
the electrode surface and the lipid bilayer. The OEG layer also ensures that
the intracellular loops of the transmembrane protein remains in a functional
state. This project is conducted together with the Chemistry Department and
detailed spectroscopical studies are undertaken in an attempt to broaden the
understanding of the phase behaviour and water binding properties of OEG-SAMs.
In the long run we hope to be able to attach lipid membrane structures on
patterned surfaces for the development of multicomponent array sensors. Micro
contact printing (uCP) is used to generate the patterned surfaces.